Bale strapping apparatus

ABSTRACT

The improved strapping apparatus comprising the present invention has been designed primarily in connection with the strapping of springy fibrous materials such as cotton or synthetic fibers while the same are held in bale form and under compression in the press box chamber of a baling press. The invention is however capable of other uses and strapping apparatus embodying the principles of the present invention may be found useful in connection with the strapping of a wide variety of other articles to which multiple strapping loops are to be applied at longitudinally spaced regions therealong. Irrespective however of the particular use to which the invention may be put, the essential features are at all times preserved.

mite States Patent 1191 Sauer et al.

1March 13, 1973 1 BALE STRAPPING APPARATUS [73] Assignee: Signode Corporation, Chicago, Ill.

[22] Filed: Oct. 18, 1971 21 Appl. No.: 190,203

UNITED STATES PATENTS 2,838,992 6/1958 Demler 100/8 UX 2,915,003 12/1959 Crosby et al. ..100/26 3,014,494 12/1961 Scott et a1 ..100/8 UX 3,475,879 11/1969 Merkel et a1 ..,.100/26 UX 3,521,550 7/1970 Van Doom et al ..100/26 Primary Examiner-Billy J. Wilhite Assistant Examiner-Philip R. Coe Attorney-Edward R. Lowndes [57] ABSTRACT The improved strapping apparatus comprising the present invention has been designed primarily in connection with the strapping of springy fibrous materials such as cotton or synthetic fibers while the same are held in bale form and under compression in the press box chamber of a baling press. The invention is however capable of other uses and strapping apparatus embodying the principles of the present invention may be found useful in connection with the strapping of a wide variety of other articles to which multiple strapping loops are to be applied at longitudinally spaced regions therealong. Irrespective however of the particular use to which the invention may be put, the essential features are at all times preserved.

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BALE STRAPPING APPARATUS In connection with certain strapping apparatus, and particularly in connection with baling presses, situations arise where it is necessary to move the strapping head to an out-of-the-way position after it has performed its last strapping operation so that it is no longer in effective strapping register with the load undergoing strapping and will not interfere with load removal operations whereby the strapped load is withdrawn from the strapping area and a new load is substituted for strapping in the next succeeding strapping cycle. Ordinarily, where the strapping head traverses the load in straight line linearfashion, pausing at each strapping location to apply a strap, it is possible to shift the strapping head to an out-of-the-way position by the simple expedient of extending the guide rails which support the travelling head-supporting carriage beyond the strapping area and causing the strapping head to continue its linear path of movement until it no longer interferes with load removal operations in the vicinity of the strapping area. However, in certain strapping installations it is not possible to thus continue the'linear path of strapping head movement due to the presence of an obstruction which interferes with such movement of either the carriage or the strapping head itself. In the case of certain baling presses, the vertical T-head construction of the baling press frame will allow linear straight-line travel of the head only to the region of the last strapping position, after which further linear movement of the head is impossible due to the presence of the vertical tensioning column of the baling press frame which constitutes the head portion of the T-head construction and which is disposed directly in the path of travel of the head.

To obviate this difficulty, the present invention contemplates the provision of a novel means for swinging the strapping head outwardly and away from the normal linear path of travel which is followed by the head during successive strap-applying operations so that after the last strapping operation on the load has been effected, the head will clear the tensioning column and come to rest in a parked" angular position where it may remain during load removal operations and sub stitution of a fresh load in the strapping area. In the case of a baling press having a T-head construction as outlined above, this will enable the press box doors to swing to their open positions without interference by the strapping head and it will also allow for such freedom of movement, either by such load removal equipment as is employed, or by the operator of the apparatus.

In the case of baling presses, as well as of certain other strapping apparatus having travelling strapping heads, sectional strap feeding chutes are employed including a front chute section which is fixedly supported by the strapping head and a rear chute section which travels with the carriage and remains permanently in register with the front chute. The two thus transversely aligned chute sections move in unison successively to the various strapping positions of which the head is capable and, at each position, they align themselves with fixed top and bottom chute sections to thus establish a continuous strap guide which encircles the load and through which the strapping head feeds the strapping preparatory to performing its usual strap tensioning operation whereby the strapping loop is shrunk upon the load. Since the front chute section is fixed to and travels with the strapping head, swinging of the head to its parked position as outlined above also shifts this chute section to an out-ofthe-way position. However the rear chute section, which similarly has a path of linear travel which is directly in line with the aforementioned obstruction, must be caused to clear this obstruction and, according to the present invention, similar means on the side of the load remote from the strapping head are provided for swinging the rear chute section away from its normal path of travel so that it also may assume a parked position where it does not interfere with load removal operations.

Such means for causing both the strapping head and the rear travelling strap chute to shift to a parked outof-the-way position after the last strap has been applied to the load constitutes one of the principal objects of the present invention and, in carrying out this object, the invention contemplates the provision of a novel quadrilateral four-bar articulated linkage mechanism including the usual fixed bar and three movable bars, the strapping head being supported on one movable bar and another movable bar constituting the crank bar of the mechanism and being provided with a cam follower roller thereon which engages the obstruction as the strapping head approaches the latter and operates the linkage mechanism automatically in such a manner that the strapping head swings out of the way and clears the obstruction at such time as the carriage moves beyond the strapping area. A similar four bar linkage mechanism is provided for the rear travelling chute, the two linkage functioning in unison to bring the strapping head and chute section to their respective parked positions simultaneously, all in a manner that will be described in detail subsequently.

Another and important feature of the present invention resides in a novel manner by means of which the strapping head is caused to traverse the load and, in so traversing the same, pause at each strapping position for strap applying operations. Heretofore, in connection with conventional means for causing a strapping head to traverse a load for multiple strap application, complicated control mechanism has been required embodying such functions and mechanisms as establishing a positive carriage drive in both directions for effecting strapping head traverse and return motions, insuring accurate centering of the strapping head and its associated chute at each strapping position, initiating carriage movement after each strapping operation to bring the strapping head to the next strapping position,

sensing the next strapping position and terminating carriage movement when such position is reached, sensing the arrival of the strapping head at each position and actuating the centering means upon such arrival, disabling the centering means after each strapping operation to allow further carriage movement to take place, as well as the performance of various other operations too numerous to mention and which are incident to such positive carriage drive.

According to the present invention, operative traversing of the load for strapping purposes is accomplished by continuously and yieldingly biasing the carriage toward its parked position and providing a series of stop surfaces, one for each strapping position, on the apparatus framework and which. are disposed directly in the path of movement of a normally projected retractible stop plunger which is provided on the carriage. Thus, as the carriage commences its operative strapping traverse of the load, the normally projected stop plunger engages the stop surface at the first strapping position and terminates movement of the carriage. At this time a strapping operation is carried out to completion and when the strap has been applied to the load and the strapping loop severed therefrom, the stop plunger is retracted from the stop surface and immediately restored to its projected position, retraction thereof releasing the continuously biased carriage and allowing it to proceed toward the next strapping position or station and the substantially immediate restoration of the plunger to its projected position causing it to be positioned properly for engagement with the stop surface at the next strapping position. The operation is repeated for each strapping station and, after the stop plunger is retracted from the last stop surface, the carriage proceeds beyond the strapping area so as to bring the strapping head and travelling chute sections to their parked positions in the manner previously outlined. This parked position of the strapping head and chutes represents the normal or idle position of the apparatus in-between successive load strapping operations and in such position all apparatus functions remain inoperative until such time as it is desired to initiate a succeeding strapping cycle. The invention is susceptible to substantially fully automatic operation and, in the exemplary illustrated form thereof, momentary depression of a start button serves automatically to return the carriage to its yieldingly biased position with the stop plunger in engagement with the stop surface at the first strapping position so as to thus commence a full strapping cycle as outlined above.

In the performance of any given strapping cycle, means are provided whereby, if desired, the strapping head may be caused to omit the application of a strap to the load at any selected strapping position or positions. Accordingly, the various stop surfaces are capable of being selectively withdrawn from the path of movement of the oncoming stop finger by prelocating them in such withdrawn positions that the continuously biased carriage will simply by-pass such strapping position and proceed automatically to the next succeeding projected stop surface where the strapping operation will take place incident to engagement of the stop finger on the carriage therewith.

The provision of a strapping apparatus such as has briefly been outlined above constitutes the principal object of the present invention. Other objects and advantages of the invention, not at this time enumerated, will become readily apparent or will be specifically pointed out as the nature of the invention is better understood.

In the accompanying four sheets of drawings forming a part of this specification, one illustrative embodiment of the invention has been shown and being operatively associated with a more or less conventional baling process.

In these drawings:

FIG. 1 is a fragmentary side elevational view of a bale strapping apparatus embodying the principles of the present invention, the full line disclosure representing the strapping head in an operative strapping position and the dotted line disclosure representing the parked condition of the strapping head;

FIG. 2 is a fragmentary end elevational view of the structure shown in FIG. 1 with a portion of the tension column broken away in the interest of clarity;

FIG. 3 is an enlarged sectional view taken substantially on the line 3-3 of FIG. 1;

FIG. 4 is a sectional view taken on the line 4-4 of FIG. 3;

FIG. 5 is a sectional view taken substantially on the line 5-5 of FIG. 2 and showing the strapping head in an operative position;

FIG. 6 is a top plan view of the structure shown in FIG. 2 as indicated by the line 6-6 but with the strapping head moved to its parked position;

FIG. 7 is an enlarged view taken substantially on the line 7-7 of FIG. 2 but showing the carriage stop plunger in its retracted position;

FIG. 8 is an enlarged sectional view similar to FIG. 7, showing the carriage stop plunger in its projected position;

FIG. 9 is a side elevational view of the structure shown in FIG. 8; and

FIG. 10 is an electrical and pneumatic circuit diagram illustrating the manner in which the operation of the strapping apparatus may be controlled.

Referring now to the drawings in detail and in particular to FIGS. 1 and 2 wherein only such portions of a baling installation as are pertinent to the present invention are disclosed, the installation embodies many of the features of a conventional press box for forming bales of cotton or other fibrous material. The installation involves in its general organization a tensioning column 10 which projects vertically upwardly from a foundation or supporting surface 12 and from the upper end of which there projects forwardly and horizontally a tubular platen-supporting beam 14 which, as shown in FIG. 2, is substantially square in cross section. Secured to the underneath side of the beam 14 is a composite upper platen 16 which, in effect, constitutes the top wall of a press box which defines a press chamber 18 for a bale B that is to be strapped by the strapping mechanism of the present invention. The full details of the press box have been omitted from the disclosure herein. For example, it is generally understood that a press box of the character with which the present invention is associated may be provided with side walls or doors which, in combination with the upper and lower platens, establish the press box chamber 18. However, in the interests of clarity, such side walls or doors have been omitted since they bear no direct relation to the invention. The extreme forward end of the beam is supported by and secured to a vertical column 20 which projects upwardly from the supporting surface 12. The columns 10 and 20, as well as the beam 14 are preferably, but not necessarily, formed of rectangular tube stock.

The upper platen 16 directly overlies the usual ejection sill 22 within which there is mounted for vertical reciprocation a lower platen 24, the latter being carried on a ram 26. As is conventional with baling installations of the character under consideration, a charging chamber (not shown) is disposed below the level of the foundation surface 12 and includes a turntable arrangement by means of which masses of the fibrous material which are loaded into the chamber are successively indexed into position immediately below the ejection sill 26 and are then pushed vertically upwardly by the lower platen 24, through the sill and into the press box chamber 18, after which each bale is compressed between the upper and lower platens 16 and 24 and thus shaped into bale form as indicated at B, preparatory to strapping of the bale.

While the bale B is disposed within the press box chamber 18 and is under compression between the upper and lower platens 16 and 24, the strapping operation is carried out, this operation consisting in the placement of a plurality'of loops or bands of metal strapping about the bale. The number of such bands will vary, of course, according to the size and length of the bale but in the form of apparatus illustrated herein facilities forstrapping the bale with six such bands 30 are provided. In order to accomplish the strapping operation a travelling strapping head 32 of conventional construction is employed, the head having facilities for receiving strapping from a suitable source, feeding it out through a guide chute which encompasses an article undergoing strapping so as to establish a closed article-encircling loop, tensioning or shrinking the loop onto the article, applying a metal seal to the overlapping portions of the closed loop, crimping the seal, and finally severing the tensioned loop from the source head for accomplishing these functions is, per se, not

novel and various commercial strapping heads are suitable for use in connection with the application of strapping to the bale B. One such head which has been found to be particularly well adapted for the purpose herein intended is manufactured by Signode Corporation of Chicago, Illinois. This strapping head is of the general type shown and described in US. Pat. No. 2,915,003, granted on Dec. 1, 1959 and entitled Power Strapping Machine.

The entire disclosure of such patent, insofar as it is consistent with the present disclosure, is hereby incorporated and made a part of this application by reference thereto. In the present application however the disclosure of the strapping head 32 is more or less schematic in its representation and it will be understood that the aforementioned facilities for handling the strapping material, i.e. paying the same outwardly through a feed chute, tensioning the loop which is established by such feed chute, and finally, applying a seal to the overlapping portions of the strapping loop when the desired degree of tension has been attained.

The present invention is concerned primarily with a novel means for effecting movement of the strapping head bodily alongside the bale B which is disposed within the press box chamber 18. Since, in the illustrated form of the invention, six bands or loops of strapping are applied to the bale, means are provided whereby the strapping head is caused to traverse the bale longitudinally in one direction from one end thereof to the other and, during such traversing operation, to pause at each of six strapping stations long enough to efi'ect a complete operation embodying the various strapping machine functions mentioned above. After the last strapping operation has been completed it is necessary that the strapping head 32 be moved to an out-of-the-way parked" position where it will not interfere with the opening of the press box doors or other operations incident to removal of the strapped bale from the pressbox, and the subsequent closing of the doors and introduction of a fresh charge of the fibrous material into the chamber 18. In the illustrated form of baling apparatus, since the width of the tensioning column 10 is appreciably greater than that of the beam 14, and since the column 10 is disposed directly in the linear path of movement of the strapping head 32, it is necessary that the head be swung to one side or otherwise moved so that it avoids such column. The manner in which this is accomplished constitutes one of the principle features of the invention. Another and important feature of the invention resides in the manner in which the strapping head is caused to locate itself accurately at each strapping station and in precise register with certain fixed positions of the strapping chute which are disposed at the various strapping stations. These and other features of the invention will be set forth in detail subsequently.

Still referring to FIGS. 1 and 2, the strapping head 32 is mounted on a travelling carriage which is designated in its entirety at 40 which moves tractionally on a pair of rails 42 and 44 by means of supporting rollers 46. More specifically, the carriage 40 is of inverted U- shape saddle-like design and includes an upper horizontal carriage frame bar 48 which is centered transversely over the beam 14 and from the ends of which there depend vertical side legs 50 and 52 which straddle the press box chamber 18. The tracks 42 and 44 are mounted on the outer ends of two pairs of lateral track supports adjacent the opposite ends of the beam 14, each pair including rear supports 54 and front supports 56 (FIG. 2), all of such supports being welded or otherwise secured to the beam 14. The various rollers 46 are rotatably mounted on respective brackets 58 and 60 carried by the legs 50 and 52, the bracket 60 also serving to support guide rollers 62 which straddle the track 44 and thus maintain the carriage 40 as a whole properly centered on the tracks 42 and 44.

The chute arrangement whereby the strapping is guided around the compressed bale at each strapping station includes a series of longitudinally fixed chute sections and a pair of travelling longitudinally movable chute sections. The fixed chute sections include an upper series 64 (FIG. 1) which is established by the fixed upper platen assembly 16 and a cooperating lower series 66 which is established by the lower platen 26. The upper series of longitudinally fixed chute sections 64 are truly fixed in that they remain stationary at all times while the lower series 66 of chute sections move with the vertically shiftable platen 24 but nevertheless remain constantly in register with the respective strapping stations with which they are associated. The travelling chute sections include a rear chute section 68 which is supported by and travels with the carriage leg 50 and a front chute section 70 which is supported by and travels with the carriage leg 52.

The chute sections 68 and 70 are so mounted on the travelling carriage 40 that as the carriage 40 traverses the various strapping stations in succession, these chute sections move into operative register with the fixed chute sections 64 and 66 which overlie and underlie the bale at such stations in order to create a closed chute path around the bale and through which the strapping material may be fed by the strapping head 32. Accordingly, the chute sections 68 and 70 are so mounted on the travelling carriage 40 that normally they are in transverse register with the strapping head 32 and remain in such transverse register therewith as the head moved successively from an initial starting position adjacent the end of the beam which is remote from the tensioning column 10 to the terminal strapping position of the head wherein the latter is in close proximity to the tensioning column 10 and immediately before the head is swung to its parked out-of-the-way position as previously described.

For the same reason that it is necessary to swing the strapping head to its out-of-the-way parked position after the last strap has been applied to the bale B, it is necessary that the two travelling chute sections 68 and 70 become similarly parked in positions which will not interfere with bale removal operations after bale strapping has been completed. To accomplish this, the front strap chute section 70 is fixedly mounted on the strapping head 32 in proper strap-receiving position so that when the head is swung to its parked position the chute section 70 will automatically move with the head to a non-interfering position. The rear strap chute section 68 is provided with individual facilities whereby, when the carriage 40 has moved past the last strapping station or position, this chute section will automatically be moved to a parked position, all in a manner that will be set forth in detail presently. It is deemed sufficient for the present to state that in the case of the strapping head 32 and its associated chute section 70, and as clearly shown in FIGS. and 6, this strapping head and its associated chute 70 are effectively supported by an articulated linkage mechanism which is designated in its entirety at 72 (FIG. 2) form the carriage leg 52, while the separate chute section 68 is similarly supported by a single upper articulated mechanism 74.

Considering now the manner in which the carriage 40, and consequently the strapping head 32 and travelling chutes 68 and 70, are caused to traverse the various strapping stations or positions, movement is imparted to the carriage under the control of a pneumatic piston and cylinder assembly 80 (FIGS. 1 and 2), supported on the rail 44 and including an elongated cylinder 82 within which there is disposed a piston 84. A first cable section 88 has one end attached to the piston and passes along one side of the rail and around a sheave 90 which is supported at one end of the rail 44. The cable section 88 makes a reverse bend and has a reentrant portion which passes along the other side of the rail and is attached to a medial region of the carriage leg 52. A second cable section 92 similarly has one end attached to the piston 84, passes over a second sheave 94 at the opposite end of the rail 44 and has its outer end attached to the leg 52. According to the invention, and as will be made clear when the pneumatic circuit diagram of FIG. is set forth, valve means are provided whereby, during the entire strapping portion of the machine cycle, air is continuously supplied to the end of the cylinder 80 adjacent the tension column 10 so as to pneumatically bias the piston 84 to the right as viewed in FIG. 1 and consequently to yieldingly urge the carriage 40 to the left. Shock absorbers 96 at the opposite ends of the track 44 are positioned in the path of travel of a pair of impact plates 98 mounted on the carriage 40 and determine the limit of movement of the carriage in either direction.

Assuming for purposes of description that the carriage 40 is in its extreme right hand position as viewed in FIG. 1 after having been restored to such position following a preceding strapping cycle of machine operation, air will be applied to the cylinder 82 as set forth above and the carriage will be biased in the direction of the tension column 10. In order to cause the strapping head 32 to move successively into register with each of the six longitudinally spaced strapping stations defined by various chute sections 64 and 66, a se ries of six carriage positioning stop pins 100 (FIGS. 1, 3, 4, 7 and 8) are carried by the rail 44 and are disposed in the linear path of movement of a retractible stop finger or plunger 102 which is carried by the front leg 52 of the carriage 40. More particularly, the various positioning stop pins 100 are disposed in a longitudinal row on the rail 44, each pin being in the form of a relatively short plunger which is slidably disposed within a cylindrical bore 104 (FIGS. 3 and 4) and which is normally maintained in the full line projected position of FIG. 3 wherein one end thereof projects laterally outwardly of the rail 44 and presents a flat plunger-engaging surface 106 designed for engagement with the stop plunger 102 on the carriage leg 52.

The various stop pins 100 and the stop finger 102 assume longitudinal positions along the rail 44 so that when the stop finger 102 is in engagement with any given stop pin 100, the strap chute section will be in accurate register with one of the chute sections 66 in the lower platen 24, as well as with the corresponding chute section 64 in the upper platen 16. At the same time, the rear travelling chute section 68 will be in register with the two fixed chute sections 66 and 64 so that initiation of the strapping operation will cause the strap to be fed endwise and completely about the bale at the particular strapping station at which the strapping head is positioned.

It is to be noted at this point that the stop plunger 102 on the carriage leg 52 is offset longitudinally from the strapping head 32 and its associated chute section 70 (FIG. 2) so that when the plunger is in engagement with a particular stop pin 100, the head and chute section are in operative register with a strapping station which is longitudinally displaced from the engaged stop pin by a distance substantially equal to the distance between adjacent stop pins 100. Stated otherwise, each stop pin establishes a strapping station or position for the strapping head 32 and its associated chute section 70, the six strapping stations being labelled a, b, c, d, e, and fin FIG. 1. The corresponding stop pins which determine these six strapping stations or positions are correspondingly labelled a, b, c, d, e andj'. It will be observed that the vertical planes of the stop pins 100 are once-removed from the vertical planes of the corresponding strapping positions, this feature being resorted to to avoid interference between certain relative moving parts as the carriage 40 is shifted.

Considering now the manner in which the stop plunger 102 is effectively mounted on the carriage leg 52, and referring specifically to FIGS. 2, 7, 8 and 9, this finger or plunger is enclosed in a cage-like supporting bracket assembly 110 (FIG. 2) having top and bottom walls 112 and 114 which are maintained spaced apart by spacer members 116. The stop plunger 102 is floatingly mounted within the bracket assembly, one end thereof being pivoted to a thrust like 118 which, in turn is pivoted at one end to the bottom wall 114. A spring pressed cylinder and thrust rod assembly 120 is pivotally connected at one end to the bottom wall 114 and at its other end to the link 118. An internal spring 121 normally maintains the assembly 120 contracted so as to project the outer end of the stop plunger 102 outwardly of the cage-like bracket assembly 110 for successive engagement with the various stop pins 100 a, b, c, d, e and f; successively and in the order named. A roller 122 which is carried at the outer end of the stop plunger 102 insures easy and frictionless withdrawal of the stop plunger from engagement with the stop sur' faces 106 on the various stop pins 100. The region of the stop plunger 102 remote from the link 118 is pivoted to one end of a shock absorber device 128 in the form of a spring biased cylinder and plunger assembly, the latter absorbing the impact against the roller as it strikes the various stop pins 100 during traverse of the carriage 40 across the bale. A limit switch LS1 is disposed in the path of swinging movement of the stop plunger 102 and, when engaged by the latter, momentarily closes an electric circuit through a solenoid valve PV (FIG. which then supplies air to the cylinder 120 and thus retracts the plunger 102 so as to withdraw the roller 122 from the stop pin 100 and allow the continuously biased carriage 40 to proceed to the next succeeding strapping position in a manner that will be set forth when the operation of the apparatus is set forth.

Referring again to FIGS. 3 and 4, means are provided whereby the various stop pins 100 may selectively be withdrawn from their normally projected positions so as to allow the carriage 40 to skip any particular strapping position if desired. Accordingly, the track 44 is provided with a threaded socket 132 in the vicinity of each plunger-receiving bore 104 and within which there is threadedly received a detent assembly 134 including a spring pressed detent ball 136. This ball is designed for cooperation with a pair of detent recesses 138 and 140 which are formed onopposite sides of theassociated stop pin 100 at longitudinally spaced regions of the latter. When the stop pin 100 assumes the position in which it is shown in full lines in FIG. 3 with the ball 136 being positioned in the recess 138, the stop pin assumes its projected position. When the stop pin is shifted inwardly in the direction of the beam 14 and rotated throughout an angle of 180 as shown in dotted lines, the ball 136 may be caused to enter the detent recess 140 and thus withdraw the projecting portion of the stop pin into the general plane of the track 44 and out of the path of movement of the roller 122 so that the carriage 40 will by-pass the particular strapping station represented by such stop pin and proceed to the next succeeding strapping station which has associated therewith a projected stop pin 100. A radially disposed handle 142 on each stop pin 100 facilitates manipulation of the latter.

Considering now the manner in which the strapping head 32 and its associated chute section 70 at the front side of the press box chamber 18, and also the rear chute section 72 at the rear side of the chamber are automatically shifted to their out-of-the-way or parked positions after the carriage and head move beyond the last strapping position or station (f), and referring first to the strapping head movements, the aforementioned articulated linkage mechanism 72 which supports the parkirighead is provided for this purpose. This linkage mechanism includes an upper linkage system 72U (FIG. 2) of the general type commonly referred to as a four bar linkage and a substantially identical lower four bar linkage system 72L. Each linkage system includes one fixed bar, two pivoted swinging bars, and one rocking bar. As will be described in greater detail presently, the respective shiftable pivot pins between adjacent bars of the upper and lower linkage systems 72U and 72L are connected together for movement in unison so that the two systems are constrained to function identically in unison. Since the two systems 72U and 72L are identical, a description of one of them will suffice for them both.

The discussion herein of the four bar linkage which is established by the four serially pivoted links 150, 158,

162 and 160 is predicated upon an article entitled Four-Bar Linkage Proportions" which appears in the publication Product Engineering in the September 19, 1960 issue thereof.

Referring now to FIGS. 5 and 6, wherein the four bar linkage 72U is clearly shown, the fixed bar of the system is represented by the vertical front leg 52 of the carriage 40, together with a pair of brackets and 152 which project laterally from opposite sides of the leg. The outer ends of the brackets 150 and 152 establish the fixed pivot points 154 and 156 of the four bar linkage system. A spider-like link 158 constitutes one of the two aforementioned pivoted bars. This latter link also constitutes the so-called crank bar of the four bar system inasmuchas it comprises the bar to which torque is-applied and which therefore, by its displacement, operates the four bar linkage system. The other pivoted bar of the four bar system is in the form of a relatively wide plate-like link 160. The link 158 is pivoted at one end to the fixed pivot point 154 while the link 160 is pivoted at one end to the fixed pivot point 156. The rocking bar of the system is in the form of a floating link 162 which is pivoted at its opposite ends to the free ends of the two pivoted links 158 and 160, the pivot points being indicated at 164 and 166.

The strapping head 32 is fixed to and swings bodily with the pivoted links 160 of the upper and lower linkage system. Accordingly, the upper and lower links are connected together by a pair of spaced apart vertical parallel crossover members 168 which straddle the strapping head 32 and have their medial regions secured to the latter by fastening screws 170 (FIG. 1). During travel of the carriage 40 from the first strapping position (a) to the last strapping position (1), the

strapping head assumes the full line position in which it is shown in FIGS. 1 and 5 wherein the longitudinal axis thereof extends at a right angle to the adjacent side of the press box chamber. This position of the strapping head is maintained by reason of a compression spring 172 which encompasses an elongated pilot rod 176. The rod 174 has one end pivoted at 175 to a short external extension 176 on the bracket 150, the rod being slidable in a pilot block 178 which is pivotally carried by a medial region of the link 160. The force which is exerted by the spring 172 against the link 160 yieldingly urges the latter in a counterclockwise direction as seen in FIG. 5, with the net result that the two links 158 and 162 are drawn into alignment, such being the nature of a four bar linkage when the rocking bar and an adjacent pivoted bar have a combined length which is shorter than the combined length of the other pivoted bar and the fixed base bar. The various links of the four bar linkage mechanism are designed according to well known four bar linkage proportioning so that when the links 158 and 162 are in alignment the strapping head 32 will assume a proper strapping position or angle as previously described.

After the carriage 40 has moved beyond the last strapping position (f) means are provided for swinging the link 158, which constitutes the crank bar of the four bar system, in a clockwise direction as viewed in FIG. so that the link 160 will be pulled by the link 162 to the dotted line position in which it is shown in FIG. 6, thus causing the strapping head to assume an angular position wherein it is moved clear of the bale B which has been fully strapped. Accordingly, the link 158 is provided with a relatively long laterally projecting deflection finger 180 which carries a cam follower-roller 182 at its outer end, the roller being designed for engagement with a generally L-shaped cam plate 184 which is secured to the tension column and lies directly in the path of movement of the roller 182 as the carriage 40 moves beyond its last strapping position 0). The cam plate presents a transversely extending impact face 186, a longitudinally extending face 188 and a connecting curved area 190. Shortly after the carriage 40 has moved away from the last strapping position (f) as shown in FIG. 5, the roller 182 engages the impact face 186 which, for the time being, prevents any further longitudinal movement of the roller. However, the linkage supporting bracket 112 continues to move downwardly as viewed in FIG. 5 so that a counterclockwise movement is imparted to the link 158, thus bringing the various elements of the four bar linkage system to the positions in which they are shown in FIG. 6 and wherein'the strapping head 32 assumes its parked out-of-the-way position clear of the tensioning column 10. During such movement of the various links, the follower roller 182 rides around the curved area 190 of the cam plate 184 and travels on the longitudinally extending face 186 of the cam plate, while at the same time the spring 172 becomes compressed so that upon return of the carriage 40 to its starting position the four bar linkage will become restored to the condition in which it is illustrated in FIG. 5.

The foregoing description of the four bar linkage system by means of which the strapping head 32 is caused to move to its parked position after the last strapping operation has been completed has been predicated largely upon a description of the upper linkage system 72U.

Since the lower linkage system 72L is substantially identical to the upper system 72U, the application of identical reference numerals to the corresponding parts thereof will suffice for a description of such latter system. It is to be noted however that the cam follower roller 182 associated with the lower linkage system cooperates with an individual cam plate 194 which is identical with the cam plate 184. In order that the upper and lower linkage systems 72U and 72L shall function in unison and in an identical manner without any tendency for binding of either system, cross over rods 196 extend between the various corresponding pivotal connections of the two systems with the exception of the connections 164 which, if connected, would bind against the strapping head 32 and thus prevent the linkage form assuming the necessary condition for parking the strapping head in its out-of-the-way position.

The strapping head 32 is supplied with strapping from a roll 200 (FIG. 1) which may be carried by a conventional strapping dispenser 202 from whence the strapping S extends vertically upwardly and passes around a pulley 204 adjacent the rear end of the apparatus and which is suitable supported on the track 44. From the pulley 204, the strapping passes to a second pulley 206 adjacent the other end of the track, after which the strapping passes over a third travelling pulley 208 which is supported by a bracket 209 from the carriage frame bar 48 (FIG. 2). From the pulley 208, the strapping passes downwardly and enters a guide tube 210 by means of which the strapping is fed to the strapping machine in a manner which is well understood in the art. It is to be noted that as the carriage 40 moves to the left as viewed in FIG. 1, the pulley 208 which substantially overlies the strapping head 32 registers vertically with the guide tube 210 so that the strapping remains in alignment with this tube in each of the strapping positions. At such time as the carriage 40 moves beyond the last strapping position (I) so that the strapping head shifts to its parked position, the section of strapping between the pulley 208 and the chute 210 assumes an'inclined position as shown in FIG. 1 but such lack of vertical register is of no consequence since no strapping is performed by the strapping head at the parked position thereof.

The embodiment of the invention disclosed herein is fully automatic in its operation, which is to say that after the apparatus is conditioned for commencement of a baling operation the strapping head 32 will perform successive strapping operations at the various strapping stations or positions a, b, c, d, e and f and then move to its parked position preparatory to'withdrawal of the strapped bale from the press box chamber 18. Moreover, when the strapping head assumes its parked condition the apparatus automatically becomes disabled until such time as the operator again conditions it for performance of the next succeeding baling operation. The various pneumatic functions associated with the apparatus are automatically operable under the control of two solenoid actuated valves, the previously mentioned plunger control valve PV and namely a carriage control valve CV. These valves hereinafter will be referred to simply as the plunger valve and the carriage valve. The valves may be mounted at any convenient position on the apparatus framework.

The operation of the herein described strapping apparatus may best be set forth with reference to FIG. 10 wherein one exemplary operative embodiment of a substantially fully automatic control system for the apparatus is disclosed. The representation of FIG. 10 is entirely schematic in its representation and consists of a simplified form of interrelated pneumatic and electrical circuitry which may be employed to attain the essential apparatus functions incident to the successive strapping of bales such as the bale B, but which is not necessarily the preferred form of such circuitry.

Before entering into a description of the operation of the apparatus, it is pointed out that for clarity of disclosure, as well as for convenience of draftsmanship, the carriage 40 is shown as assuming a mid-position along the track 44 after the roller 122 has engaged one of the stop pins 100 so that the strapping head 32 is about to commence a strapping operation. The condition of the contacts associated with the limit switches, together with certain other contacts yet to be described, is the normal condition thereof incident to the particular point in the apparatus cycle thus illustrated. The operation of the circuitry will however be set forth on the basis of the apparatus being in its idle condition with the carriage 40 disposed at the left hand end of the track 44 and with the strapping head 32 and its associated travelling chutes 68 and 70 assuming their parked positions as previously described.

Upon closure of the master switch MS, current will be made available from the source (which may be a conventional power line) for operation of the apparatus. Prior to depression of the start button SB, for the purpose of initiating the various apparatus functions, the solenoid valve SV2 remains deenergized and is thus spring biased to its normal position wherein air is conducted from a source S2 of air under pressure through line 250, carriage valve'CV, and line 252 to the left hand end of the cylinder 82, thus forcing the piston 84 to the right and holding the carriage 40 in its extreme left hand end. position as determined by the shock absorber 96 (FIG. 1) at this end of the track 44. Momentary depression of the start button SB will establish an electrical circuit extending from the positive side of the line through leads 11,13, start button SB, leads 15, 17, relay magnet RM, and leads 19, 21 back to the negative side of the line Upon energization of the relay magnet RM, a locking or holding circuit becomes effective, this circuit extending through leads 11, 23, 25, normally closed contacts of the limit switch LS2, lead 27, No. 1 contacts of the magnet RM, leads 29, 17, magnetRM and leads 19, 21 back to-the line.

The No. 1 holding contacts of the magnet RM perform a dual function, in that closure thereof also establishes a circuit through the winding wl of the car riage valve CV, this circuit extending through leads 11, 23, 25, contacts of the switch LS2, lead 27, No. 1 contacts of the magnet RM, leads 29, 31, winding wl of the valve CV and leads 33, 21 back to the line. Energization of the winding wl causes the valve CV to.- shift its position so that air is caused to flow through line 250, valve CV, and line 254 to the right hand end of the cylinder 82, thus forcing the piston to the left and causing the carriage 40 to move away from. the shock absorbel' and proceed forwardly along the track 44 until such time as it engages theshock absorber 96 at the other end of the track and also engages the limit switch LS2 so as to open the normally closed contacts thereof. Upon initial energization of the relay magnet RM incident to depression of the start button SB as previously described, the No. 2 contacts of this magnet also become closed so as to establish a circuit through the winding W2 of the solenoid valve PV to thereby retract the stop plunger 102 during forwardv travel of the carriage 40 so that the roller 122 thereon will move clear of the various stop pins 100. The circuit by means of which the winding w2 becomes energized extends from the line, through leads ll, 23, 35, No. 2 contacts of the magnet RM, leads 37, 39, winding w2, and leads 41, 21 back to the line.

As soon as the carriage 40 reaches the end of its forward stroke, the normally closed contacts of the limit switch LS2 become open, thus deenergizing the relay magnet circuit and opening the No. l and No. 2 contacts of this magnet. Opening of the No. 1 contacts serves to deenergize the previously described circuit through the winding wl of the carriage valve and opening of the No. 2 contacts serves to deenergize the aforementioned circuit through the winding w2 of the plunger valve PV. Deenergization of the winding wl restores the carriage valve to its normal condition wherein the carriage is air biased to the left in the direction of the tensioning column 10, while deenergization of the winding w2 restores the plunger valve to its normal condition where the supply of air to the cylinder 120 is discontinued, thus allowing the spring biased stop plunger to become projected for successive engagement with the stop pins during the operative strap-applying cycle of carriage movement.

As soon as the roller 122 on the stop plunger 102 engages the first stop pin on the track 44, the articulated mechanism within the cage-like bracket assembly (FIGS. 2, 7, 8 and 9) causes the contacts of the limit switch LS1 to become closed. For the time being, no function will take place as a result of the closure of these contacts inasmuch as the strapping machine contacts S3 remain open as previously described until the strapping operation has taken place. At the completion of such strapping operation, closure of these contacts S3 will establish a circuit which extends through leads 43, contacts S3, lead 45, contacts LS1, lead 39, winding w2. of the plunger valve PV, and leads 41, 21 back to the line. Energization of the winding w2 causes air to be conducted through conduit 256, valve PV, and conduit 258 to the cylinder which function in the manner previously described to momentarily retract the stop plunger 102 and withdraw the roller 122 from the stop pinl00. As soon as the roller has cleared the stop pin 100, the air-biased carriage 40 is free to move toward the next strapping station or position, whereupon the contacts of the switch LS1 become open and immediately restore the plunger 102 to its projected position due to opening of the circuit through the winding w2 of the plunger valve PV and consequent discontinuance of air to the cylinder 120. With the stop plunger 102 thus projected, the carriage travels toward the next strapping position and comes to rest as soon as the roller 122 engages the stop pin 100 associated with such station. This intermittent movement of the carriage 40, accompanied by the performance of strapping operations at each strapping position takes place repeatedly until the carriage is released from the last strapping position and moves toward the tensioning column 10 so that swinging movements of the strapping head 32 and the rear chute section 68 (FIG. 6) to their parked positions will take place under the influence of the cams 184 on the tensioning column in the manner previously set forth.

Upon arrival of the carriage 40 at the parking position the shock absorber 96 will terminate further movement thereof and the air bias which is continuously placed upon the piston 84 within the cylinder 82 will serve to maintain the carriage in such position against drifting. Since at this time all of the electrical contacts associated with the apparatus are open, all electrical functions are disabled and the apparatus awaits depression of the start button SB for performance of the next bale strapping operation.

The invention is not t be limited to the exact arrangement of parts shown in the accompanying drawings or described in this specification as various changes in the details of construction may be restored to without departing from the spirit of the invention. For example, although a cable and air cylinder is disclosed herein as being the means for continuously applying a bias to the carriage 40 to move the same each time the stop plunger 102 is withdrawn from a given stop pin 100, other biasing means such as a fluid motor which is capable of stalling when its output is exceeded, an electric torque motor, a slip clutch or, in the case of small strapping apparatus a spring means. Additionally numerous other forms of abutments may be provided on the framework of the apparatus in place of the illustrated stop pins 100. It is also within the purview of the invention to utilize automatically retractible stop plungers on the framework in combination with a fixed stop pin or finger on the travelling carriage. Still further, the invention is equally applicable to strapping apparatus employing a stationary strapping head which is traversed by the load undergoing strapping. In any event, modifications will be resorted to as required. The invention therefore is to be limited only insofar as it has been pointed out in the accompanying claims.

Having thus described the invention what we claim and desire to secure by letters patents is:

l. in a strapping apparatus for successively applying strapping loops to an article at longitudinally spaced locations therealong, a framework establishing a strapping station, a guide chute section at each location for conducting strapping endwise across said station to establish a loop thereat, a longitudinally shiftable carriage on said framework, a strapping head mounted on said carriage for feeding lengths of strapping endwise into said chutes, means yieldingly baising said carriage in one longitudinal direction along the framework to bring the strapping head into successive register with said chute sections for strap feeding purposes, and retractible limit stop means effective between the framework and carriage for arresting movement of the latter at each strapping region at such time as the strapping head moves into effective register with the chute section at such region.

2. In a strapping apparatus, the combination set forth in claim 1, wherein said retractible limit stop means comprises a plunger mounted on the carriage for movement between a projected and a retracted position, a plurality of longitudinally spaced impact surfaces on the framework and normally positioned in the path of movement of the plunger when the latter is projected and the carriage moves in said one direction, and means for moving said plunger between its projected and its retracted positions.

3. In a strapping apparatus, the combination set forth in claim 2, wherein said impact surfaces are individually retractible out of said path of movement of the projected plunger, and means are provided for selectively maintaining said impact surfaces in their retracted positions.

4. In a strapping apparatus, the combination set forth in claim 1, wherein said retractible limit stop means comprises a plunger mounted on the carriage for move ment between a projected and a retracted positions, means normally maintaining said plunger in its projected position, a row of longitudinally spaced stop pins on the framework and normally positioned in the path of movement of the plunger when the latter is projected and the carriage moves in said one direction, and means automatically effective upon engagement of said plunger with each stop pin for momentarily retracting the plunger to restore the same from such engagement and immediately restoring it to its projected position for subsequent engagement with the next succeeding stop pin in the row.

5. In a strapping apparatus, the combination set forth in claim 4, wherein said plunger is provided with an anti-friction roller on its outer end, and each stop pin is formed with a planar impact surface which is normal to the direction of movement of the roller and which is designed for engagement with the latter.

6. In a strapping apparatus, the combination set forth in claim 4, wherein said stop pins are individually retractible out of the path of movement of the projected plunger, and detent means are provided for selectively maintaining said stop pins in their normal and their retracted positions.

7. Apparatus for successively applying strapping loops at longitudinally spaced locations to a bale of fibrous material which is maintained under compression within the press box of a baling machine by means of a fixed upper platen and a vertically reciprocable lower platen, said platens being provided with a pair of cooperating transversely extending upper and lower horizontal guide chute sections at each location for conducting strapping transversely across the press box during establishment of a loop, said apparatus comprising a longitudinally extending guide rail disposed above the press box, a carriage tractionally supported on said rail and having front and rear depending side legs which straddle the press box, a strapping head mounted on said front leg and having upper and lower vertical front chute sections thereon designed for successive register with said horizontal chute sections, a vertical rear chute section on said rear leg and likewise designed for successive register with said horizontal chute sections, said rear chute section being in transverse alignment with said front chute sections whereby simultaneous register of the front and rear chute sections with each pair of horizontal chute sections is attained and means for moving said carriage along said guide rail to bring said front and rear chute sections successively into register with the horizontal chute sections.

8. Apparatus for successively applying strapping loops to a bale of fibrous material as set forth in claim 7, wherein said means for moving the carriage comprises an pneumatic means normally and yieldingly biasing said carriage in one longitudinal direction, releasable limit stop means effective between the carriage and guide rail for arresting movement of the former at such time as the front and rear chute sections assume positions of register with said horizontal chute sections.

9. Apparatus for successively applying strapping loops to a bale of fibrous material as set forth in claim 8, wherein said releasable limit stop means comprises a stop plunger mounted on said carriage for movement between a projected and a retracted position, and a row of longitudinally spaced stop pins mounted on said rail and normally positioned in the path of movement of said plunger when the latter is in its projected position, means normally maintaining said plunger in its projected position, and means automatically effective upon engagement of the plunger with a stop pin for momentarily retracting the plunger and immediately thereafter restoring the same to its projected position.

10. Apparatus for successively applying strapping loops at longitudinally spaced locations to an article positioned at a strapping action, a framework establishing said station, guide chutes at each location through which strapping material is adapted to be projected endwise to establish said loops, a carriage movable longitudinally on said framework, a strapping head mounted on said carriage and movable bodily therewith, means for shifting said carriage longitudinally in one direction to move the strapping head through the strapping station in linear fashion and bring the same into successive register with said guide chutes for projection of strapping material thereto and thereafter to shift the strapping head beyond said strapping station, and means automatically effective after said head has moved beyond said strapping station for shifting the same on said carriage to a position which is transversely offset from its longitudinal path of travel through the strapping station.

11. Apparatus as set forth in claim 10, wherein said strapping head is pivoted to the carriage for swinging movement about a horizontal axis, toward and way from said path of travel, and said automatically effective means constrains the head to swing away from said path of travel.

12. Apparatus as set forth in claim 10, wherein said automatically effective means comprises a link pivotally connected at one end to the carriage and on which the strapping head is fixedly mounted, and cam means effective between said framework and link for swinging the latter, and consequently the head, outwardly away from said path of travel.

13. Apparatus as set forth in claim 10, wherein said automatically effective means comprises an articulated four bar linkage system mounted on said carriage and including a fixed bar, a pair of swinging bars pivoted at their proximate ends to said fixed bar, and a rocker bar pivoted at its ends to the distal ends of the pivoted bars, said strapping head being mounted one one of said pivoted bars, and an abutment on said framework and engageable with the other pivoted bar for effecting articulation of the linkage system to thus shift the strapping head to said offset position.

14. Apparatus as set forth in claim 13, wherein the respective lengths of said bars are such that when said strapping head moves through the strapping station said other pivoted bar and the rocker bar are in alignment and thus maintain the strapping head in alignment with the guide chutes at the various locations. 

1. In a strapping apparatus for successively applying strapping loops to an article at longitudinally spaced locations therealong, a framework establishing a strapping station, a guide chute section at each location for conducting strapping endwise across said station to establish a loop thereat, a longitudinally shiftable carriage on said framework, a strapping head mounted on said carriage for feeding lengths of strapping endwise into said chutes, means yieldingly baising said caRriage in one longitudinal direction along the framework to bring the strapping head into successive register with said chute sections for strap feeding purposes, and retractible limit stop means effective between the framework and carriage for arresting movement of the latter at each strapping region at such time as the strapping head moves into effective register with the chute section at such region.
 1. In a strapping apparatus for successively applying strapping loops to an article at longitudinally spaced locations therealong, a framework establishing a strapping station, a guide chute section at each location for conducting strapping endwise across said station to establish a loop thereat, a longitudinally shiftable carriage on said framework, a strapping head mounted on said carriage for feeding lengths of strapping endwise into said chutes, means yieldingly baising said caRriage in one longitudinal direction along the framework to bring the strapping head into successive register with said chute sections for strap feeding purposes, and retractible limit stop means effective between the framework and carriage for arresting movement of the latter at each strapping region at such time as the strapping head moves into effective register with the chute section at such region.
 2. In a strapping apparatus, the combination set forth in claim 1, wherein said retractible limit stop means comprises a plunger mounted on the carriage for movement between a projected and a retracted position, a plurality of longitudinally spaced impact surfaces on the framework and normally positioned in the path of movement of the plunger when the latter is projected and the carriage moves in said one direction, and means for moving said plunger between its projected and its retracted positions.
 3. In a strapping apparatus, the combination set forth in claim 2, wherein said impact surfaces are individually retractible out of said path of movement of the projected plunger, and means are provided for selectively maintaining said impact surfaces in their retracted positions.
 4. In a strapping apparatus, the combination set forth in claim 1, wherein said retractible limit stop means comprises a plunger mounted on the carriage for movement between a projected and a retracted positions, means normally maintaining said plunger in its projected position, a row of longitudinally spaced stop pins on the framework and normally positioned in the path of movement of the plunger when the latter is projected and the carriage moves in said one direction, and means automatically effective upon engagement of said plunger with each stop pin for momentarily retracting the plunger to restore the same from such engagement and immediately restoring it to its projected position for subsequent engagement with the next succeeding stop pin in the row.
 5. In a strapping apparatus, the combination set forth in claim 4, wherein said plunger is provided with an anti-friction roller on its outer end, and each stop pin is formed with a planar impact surface which is normal to the direction of movement of the roller and which is designed for engagement with the latter.
 6. In a strapping apparatus, the combination set forth in claim 4, wherein said stop pins are individually retractible out of the path of movement of the projected plunger, and detent means are provided for selectively maintaining said stop pins in their normal and their retracted positions.
 7. Apparatus for successively applying strapping loops at longitudinally spaced locations to a bale of fibrous material which is maintained under compression within the press box of a baling machine by means of a fixed upper platen and a vertically reciprocable lower platen, said platens being provided with a pair of cooperating transversely extending upper and lower horizontal guide chute sections at each location for conducting strapping transversely across the press box during establishment of a loop, said apparatus comprising a longitudinally extending guide rail disposed above the press box, a carriage tractionally supported on said rail and having front and rear depending side legs which straddle the press box, a strapping head mounted on said front leg and having upper and lower vertical front chute sections thereon designed for successive register with said horizontal chute sections, a vertical rear chute section on said rear leg and likewise designed for successive register with said horizontal chute sections, said rear chute section being in transverse alignment with said front chute sections whereby simultaneous register of the front and rear chute sections with each pair of horizontal chute sections is attained and means for moving said carriage along said guide rail to bring said front and rear chute sections successively into register with the horizontal chute sections.
 8. Apparatus for successively applying strapping loops tO a bale of fibrous material as set forth in claim 7, wherein said means for moving the carriage comprises an pneumatic means normally and yieldingly biasing said carriage in one longitudinal direction, releasable limit stop means effective between the carriage and guide rail for arresting movement of the former at such time as the front and rear chute sections assume positions of register with said horizontal chute sections.
 9. Apparatus for successively applying strapping loops to a bale of fibrous material as set forth in claim 8, wherein said releasable limit stop means comprises a stop plunger mounted on said carriage for movement between a projected and a retracted position, and a row of longitudinally spaced stop pins mounted on said rail and normally positioned in the path of movement of said plunger when the latter is in its projected position, means normally maintaining said plunger in its projected position, and means automatically effective upon engagement of the plunger with a stop pin for momentarily retracting the plunger and immediately thereafter restoring the same to its projected position.
 10. Apparatus for successively applying strapping loops at longitudinally spaced locations to an article positioned at a strapping action, a framework establishing said station, guide chutes at each location through which strapping material is adapted to be projected endwise to establish said loops, a carriage movable longitudinally on said framework, a strapping head mounted on said carriage and movable bodily therewith, means for shifting said carriage longitudinally in one direction to move the strapping head through the strapping station in linear fashion and bring the same into successive register with said guide chutes for projection of strapping material thereto and thereafter to shift the strapping head beyond said strapping station, and means automatically effective after said head has moved beyond said strapping station for shifting the same on said carriage to a position which is transversely offset from its longitudinal path of travel through the strapping station.
 11. Apparatus as set forth in claim 10, wherein said strapping head is pivoted to the carriage for swinging movement about a horizontal axis, toward and way from said path of travel, and said automatically effective means constrains the head to swing away from said path of travel.
 12. Apparatus as set forth in claim 10, wherein said automatically effective means comprises a link pivotally connected at one end to the carriage and on which the strapping head is fixedly mounted, and cam means effective between said framework and link for swinging the latter, and consequently the head, outwardly away from said path of travel.
 13. Apparatus as set forth in claim 10, wherein said automatically effective means comprises an articulated four bar linkage system mounted on said carriage and including a fixed bar, a pair of swinging bars pivoted at their proximate ends to said fixed bar, and a rocker bar pivoted at its ends to the distal ends of the pivoted bars, said strapping head being mounted one one of said pivoted bars, and an abutment on said framework and engageable with the other pivoted bar for effecting articulation of the linkage system to thus shift the strapping head to said offset position. 